Background L-type calcium channel participates in the regulation of a variety of physical and pathological process. In vasculature, it mainly mediated agonist-induced vascular smooth muscle contraction. However, it is not clear whether there are differences in L-type calcium channel mediated vessel responses to certain vasoconstrictors among different species. Methods The coronary arteries were dissected from the heart of rats and mice respectively. The coronary arterial ring contraction was measured by Multi Myograph System. Results Endothelin-1, U46619 and 5-HT could produce concentration-dependent vasoconstriction of coronary arterial rings from rats and mice. Compared with rats, the vessel rings of mice were more sensitive to ET-1 and U46619, and less sensitive to 5-HT. The L-type Ca2~ channel blocker nifedipine could significantly inhibit the coronary artery contractions induced by ET-1, U46619 and 5-HT. The inhibitory effect of i ixM nifedipine on ET-1 and 5-HT-induced coronary artery contractions were stronger in mice than in rats, but its effect on U46619 induced-vessel contractions was much weaker in mice than in rats. Conclusions L-type Ca2＋ channel plays an important role in the coronary arterial contraction, but the responses to vasoconstrictor and L-type Ca2＋ channel blocker are different between rats and mice, thus suggesting that the coronary arteries of rats and mice have different biological characteristics.
Carvedilol, nonselective β-adrenoreceptor antagonist, was showed protective effects against acute myocardial infarction （AMI）-induced myocardial injury, however, the mechanisms underlying the anti- fibrosis effect of carvedilol has not been well known. The aim of the present study was to investigate the potential mechanism for the anti-fibrosis effect of carvedilol against AMI-induced myocardial fibrosis in rats. Methods Male SD rats were randomized into the sham group, LAD surgery-AMI model group, AMI plus low dose of carvedilol treatment group （1 mg/kg per day, CAR-L）, AMI plus medium dose of carvedilol treatment group （5 mg/kg per day, CAR-M） and AMI plus high dose of carvedilol treatment group （10 mg/kg per day, CAR-H）. The passage 3 neonatal SD rat cardiac fibroblasts were used for hypoxia/normoxia （2 h/4 h） treatment in the presence of carvedilol （0, 1, 2 and 4 μM）. Results Cardiac remodeling and impaired heart function were observed after 14-week LAD surgery treatment, however, and the cardiac remodeling and decreased ejection fraction （EF%） and fractional shortening （FS%） were efficiently rescued in the CAR-M and CAR-H groups. The up-regulated expressions of Collal, Col3al and tx-SMA at mRNA and protein levels were significantly reduced in the CAR-M and CAR-H groups. The in vitro study showed that Collal, Col3al and ot- SMA expressions at both mRNA and protein levels were down-regulated by carvedilol in rat cardiac fibroblasts in a dose-dependent manner. Smad3 inhibitors, SIS-3 and naringenin, could efficiently decrease Collal, Col3al and α-SMA expressions in rat cardiac fibroblasts. Smad3 was shown significantly inactivated in carvedilol-treated rat cardiac fibroblasts. Conclusion Carvedilol negatively regulates Smad3 signal pathway and inhibits extracellular matrix related Collal, Col3al and α-SMA expressions, contributing to the anti-fibrosis effect of carvedilol against AMI-induced myocardial fibrosis in rats.
Background MicroRNAs （miRNANAs） are endogenous, small non-coding RNAs that negatively regulate gene expression in diverse cardiovascular diseases. However, the roles of miRNANAs in atherosclerogenesis needs to be elucidated. In the present study, the effect of miRNA-21 on pro-atherosclerotic genes expression was examined. Methods The pro-atherosclerotic genes including COX2, VCAM1, ICAM1, MCP1 and miRNA-21 were detected in ox-LDL-treated mouse macrophage RAW264.7 cells. ApoE knock-out （ApoE- KO） mice were fed with high-fat diet for 16 weeks, and the abdominal aorta were fixed and used for miRNA- 21 hybridization. Lentivirus-based vectors for enforced expression of miRNA-21 and antisense miRNA-21were prepared. The expression of proatherosclerotic genes was determined in the RAW264.7 cells with lentivirus- mediated up-regulation of miRNA-21. Results COX2, VCAM1, ICAM1 and MCP1 could be up-regulated by ox-LDL treatment, and 50 Ixg/mL ox-LDL could significantly increase the expression of above four genes in ox-LDL EAW264.7 cells, miRNA-21 could also be markedly up-regulated in ox-LDL-induced RAW264.7 cells. The result of miRNANA hybridization showed that miRNA-21 was strongly expressed in atherosclerotic plaques but not in normal aorta. Lentivirus-mediated over-expression of miRNA-21 could significantly enhance expressions of COX2, VCAM1, ICAM1 and MCP1 in RAW264.7 cells, which could be reversed by antisense miRNA-21 mediated by lentivirus vector. Conclusions miRNA-21 could be modulated by ox-LDL in macrophage RAW264.7 cells, and miRNA-21 could enhance COX2, VCAM1, ICAM1 and MCP1 expressions in macrophages.
